Application of Doppler ultrasound velocimetry in multiphase flow

This work aims to extend the application of a commercial Doppler ultrasound velocimetry DOP2000 (Model 2030, signal processing S.A.) to multiphase systems. We firstly make a correction to the determination of Doppler angle and measuring location taking into account the ultrasound refraction and the ultrasound velocity difference in different medias, and then investigate the measurement of the solid concentration in a liquid-solid system and the bubble behavior in a gas-liquid system with low gas holdup. The experimental results show that the attenuation coefficient increases monotonously. A model based on the ultrasound reflection and refraction law is proposed to predict the received echo energy in homogeneous liquid-solid system. Furthermore, the signal response of bubbles is also discussed. By placing the probe in the direction of the flow, the difficulty of determining Doppler angle is avoided and the liquid and bubble rise velocities are simultaneously obtained. (C) 2002 Elsevier Science B.V. All rights reserved.